1. Field of the Invention
The present invention relates to the determination of current and power consumption by circuit. More particularly, the present invention relates to a method for realistic current and power analysis.
2. Art Background
Although current and power consumption analysis of a circuit has been performed in the past, only recently, with the increasing focus on circuit design for portable computing devices, has the need for accurate calculation of current and power consumption early in the design process of the circuit become increasingly important. In addition, greater chip densities, more stringent design rules and higher operating frequencies call for stricter, more realistic power analysis and power bus design early in the design cycle, prior to fabrication on silicon.
Evaluation of power and power saving features can be performed once the circuit has been fabricated, i.e., after first silicon. This has obvious drawbacks such as redesigning the circuit late in the design cycle and hence, increasing the period of time from initial design to market. Moreover, even after first silicon, only the total current/power consumed by the chip as a whole can be obtained. The estimation of current/power consumed by each module/unit inside the chip during various debugging phases is still very difficult to obtain and typically inaccurate.
In the past, device counts of a circuit were used to estimate power. The number of each type of device and the typical power/current consumption by a device type were then used to generate a rough estimate of the current and power consumed.